Mix the flour, baking powder, powdered sugar, salt, and eggs. Add the butter and mix well. Add water and knead until obtaining a firm mixture.
Add blueberries to taste and knead again to evenly distribute the blueberries. Use a rolling pin and knead until obtaining a 0.1-inch (3 mm) thickness.
Cut the dough into 4 x 2 inches rectangles, then make a vertical cut of about 3 cm, and make the characteristic fold for calzones rotos.
Fry the calzones rotos for around one minute, drain, and put in a dish. Add powdered sugar to taste.